Observer模式

Observer.java

观察者

public interface Observer { void update(NumberGenerate numberGenerate); }

　　

DigitObserver.java

数字观察者

public class DigitObserver implements Observer { @Override public void update(NumberGenerate numberGenerate) { System.out.println("DigitObserver: " + numberGenerate.getNumber()); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } }

 

GraphObserver.java

图像观察者

public class GraphObserver implements Observer { @Override public void update(NumberGenerate numberGenerate) { System.out.println("GraphObserver: "); int count = numberGenerate.getNumber(); for (int i = 0; i < count; i++) { System.out.print("*"); } System.out.println(); try { Thread.sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } } }

 

NumberGenerate.java

被观察者的抽象类

public abstract class NumberGenerate { private List<Observer> observers = new ArrayList<>(); public void addObserver(Observer observer) { //注册observer observers.add(observer); } public void deleteobserver(Observer observer) { //删除observer observers.remove(observer); } public void notifyObservers() { //向observer发送通知 Iterator it = observers.iterator(); while (it.hasNext()) { Observer o = (Observer) it.next(); o.update(this); } } public abstract int getNumber();//获取数值 public abstract void execute();//生成数值 }

　　

RandomNumberGenerator.java

被观察者-随机数生成器

public class RandomNumberGenerator extends NumberGenerate { private Random random = new Random(); private int number; @Override public int getNumber() { return number; } @Override public void execute() { for (int i = 0; i < 20; i++) { number = random.nextInt(50); notifyObservers(); } } }

　

Main.java　

测试类

public class Main { public static void main(String[] args) { NumberGenerate generate = new RandomNumberGenerator(); Observer observer1 = new DigitObserver(); Observer observer2 = new GraphObserver(); generate.addObserver(observer1); generate.addObserver(observer2); generate.execute(); } }

　　

运行结果:

 

 

　　

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

　　

转载于:https://www.cnblogs.com/Hangtutu/p/9252443.html

相关资源：数据结构—成绩单生成器